Battery pack having reinforcement member

ABSTRACT

Disclosed is a battery pack including a battery module array, wherein a reinforcement member is coupled to side walls of end plates or sides of main members at an outer side of an outermost battery module of the battery module array to minimize deformation of the battery pack when the battery pack is vibrated in the front and rear direction.

TECHNICAL FIELD

The present invention relates to a battery pack having a reinforcementmember, and, more particularly, to a battery pack including a batterymodule array having battery modules which are arranged in the lateraldirection in two or more rows, a base plate on which the battery modulesare stacked in a vertically erected state, a pair of main membersprovided at the front and rear of the battery module array to supportload of the battery modules, opposite ends of each of the main membersbeing fastened to an external device, a pair of end plates disposed intight contact with the front and rear of the battery module array in astate in which the lower end of each of the end plates is fixed to thebase plate, and supporting bars connected between upper parts or sideparts of the end plates so as to interconnect and support the endplates, wherein a reinforcement member is coupled to side walls of theend plates or sides of the main members at the outer side of anoutermost battery module of the battery module array to minimizedeformation of the battery pack when the battery pack is vibrated in thefront and rear direction.

BACKGROUND ART

One of the biggest problems caused by vehicles using fossil fuel, suchas gasoline and diesel oil, is the creation of air pollution. Atechnology of using a secondary battery, which can be charged anddischarged, as a power source for vehicles has attracted considerableattention as one method of solving the above-mentioned problem. As aresult, electric vehicles (EV), which are operated using only a battery,and hybrid electric vehicles (HEV), which jointly use a battery and aconventional engine, have been developed. Some electric vehicles andhybrid electric vehicles are now being commercially used. A nickel-metalhydride (Ni-MH) secondary battery has been mainly used as the powersource for electric vehicles (EV) and hybrid electric vehicles (HEV). Inrecent years, however, the use of a lithium-ion battery has beenattempted.

High power and capacity are needed for such a secondary battery to beused as the power source for the electric vehicles (EV) and the hybridelectric vehicles (HEV). To this end, a plurality of small-sizedsecondary batteries (unit cells) is connected in series to each other soas to form a battery module and a battery pack. According tocircumstances, a plurality of small-sized secondary batteries (unitcells) is connected in series and in parallel to each other so as toform a battery module and a battery pack.

Generally, such a battery pack has a structure to protect batterymodules, each of which has secondary batteries mounted therein. Thestructure of the battery module may be varied based on the kind ofvehicles or installation position of the battery pack in the vehicles.One of the structures to effectively fix high-capacity battery modulesis based on supporting bars and end plates. This structure isadvantageous in that movement of the battery modules is minimized evenwhen load is applied toward the supporting bars. To this end, however,it is necessary to sufficiently secure rigidity of the supporting barsand end plates.

In connection with this case, FIG. 1 is a perspective viewillustratively showing a conventional battery pack including a singlebattery module.

Referring to FIG. 1, a battery pack 100 includes unit modules 10, eachof which has secondary batteries mounted therein, a base plate 20, apair of end plates 30, and supporting bars 40.

The unit modules 10 are stacked at the top of the base plate 20 in astate in which the unit modules 10 are vertically erected. The endplates 30 are disposed in tight contact with the outer sides of theoutermost unit modules 10 in a state in which the lower end of each ofthe end plates 30 is fixed to the base plate 20.

The supporting bars 40 are connected between the upper parts of the endplates 30 so as to interconnect and support the end plates 30.

However, the battery pack with the above-stated construction does notinclude a structure to support the battery pack in the front and reardirection of the battery pack when external force is applied to thebattery pack in the front and rear direction of the battery pack withthe result that it is not possible to prevent deformation of the batterypack.

Also, the battery pack with the above-stated construction uses only asingle battery module with the result that the capacity of the batterypack is low. For this reason, it is difficult for the battery pack withthe above-stated construction to be applied to an external device, suchas a vehicle, which needs a high power and capacity battery pack.

Meanwhile, battery packs for hybrid electric vehicles are configured invarious forms based on the kind of vehicles or installation position ofthe battery pack in the vehicles so as to stably protect a battery cellarray. Among such battery packs is a battery pack having a bucketstructure, which is installed in the lower part of a trunk of a vehicleor in a depressed space defined between the lower end of a rear seat andthe trunk of the vehicle.

In this case, the battery pack is located below the place at which thebattery pack is fastened to the chassis of the vehicle. Consequently, itis necessary to provide a structure in which the battery pack issupported by main members and a base plate, and end plates andsupporting bars are located at the front and rear of the battery pack soas to prevent the battery pack from being deformed in the front and reardirection. In this structure, the main members are bent in the shape ofa bucket, and therefore, the overall structural stability of the batterypack is decided depending upon rigidity of the main members.

The rigidity of the main members may be improved by sufficientlyincreasing the depth of a flange or the thickness of each of the mainmembers. However, it is not possible to sufficiently increase the depthof the flange due to the limited installation space in the vehicle.Also, increasing the thickness of each of the main members increasesload of the battery pack. As a result, it is not possible to improve thestructural stability of the battery pack.

Therefore, there is a high necessity for a battery pack configured tohave a structure in which battery modules are located below the place atwhich the battery pack is fastened to the chassis of a vehicle, mainmembers to support load of the battery pack have a bucket form, and thebattery modules are arranged on a base plate in two rows, wherebystructural stability of the battery pack is improved while the depth ofa flange and the thickness of each of the main members are maintained,and deformation of the battery pack is minimized when external force isapplied to the battery pack in the front and rear direction.

DISCLOSURE Technical Problem

Therefore, the present invention has been made to solve the aboveproblems, and other technical problems that have yet to be resolved.

Specifically, it is an object of the present invention to provide abattery pack including a battery module array having battery moduleswhich are arranged in the lateral direction in two or more rows, a baseplate, main members, end plates, and supporting bars, wherein areinforcement member is coupled to side walls of the end plates or sidesof the main members at the outer side of an outermost battery module ofthe battery module array to minimize deformation of the battery packwhen the battery pack is vibrated in the front and rear direction.

It is another object of the present invention to provide a battery packconfigured to have a structure in which a portion of the battery pack isformed using a portion of a vehicle so that the battery pack can bestably installed in the vehicle and the volume occupied by the batterypack in the vehicle can be minimized.

Technical Solution

In accordance with one aspect of the present invention, the above andother objects can be accomplished by the provision of a battery packincluding a battery module array having battery modules which arearranged in the lateral direction in two or more rows, each of thebattery modules being configured to have a structure in which batterycells or unit modules, each of which has two or more battery cellsmounted therein, stacked in a state in which the battery cells or theunit modules are vertically erected, a base plate on which the batterymodules are stacked in a vertically erected state, a pair of mainmembers provided at the front and rear of the battery module array tosupport load of the battery modules, opposite ends of each of the mainmembers being fastened to an external device, a pair of end platesdisposed in tight contact with the front and rear of the battery modulearray in a state in which the lower end of each of the end plates isfixed to the base plate, and supporting bars connected between upperparts or side parts of the end plates so as to interconnect and supportthe end plates, wherein a reinforcement member is coupled to side wallsof the end plates or sides of the main members at the outer side of anoutermost battery module of the battery module array to minimizedeformation of the battery pack when the battery pack is vibrated in thefront and rear direction.

In the battery pack according to the present invention, thereinforcement member is coupled to the side walls of the end plates orthe sides of the main members. Consequently, it is possible to preventdeformation of the battery pack when the battery pack is vibrated in thefront and rear direction.

Also, the opposite ends of each of the main members are fastened to anexternal device. Even when the battery pack is located below the placeat which the battery pack is fastened to the external device, therefore,it is possible to easily mount the battery pack to the external device.

In addition, the battery modules, in which the unit modules are stackedin a state in which the unit modules are vertically erected, arearranged in the lateral direction in two or more rows. Consequently, itis possible for the battery pack according to the present invention toprovide higher power and capacity than a conventional battery packincluding a single battery module.

In the present invention, each of the unit modules may be a secondarybattery or a small-sized module having two or more secondary batteriesmounted therein. An example of a unit module having two or moresecondary batteries mounted therein is disclosed in Korean PatentApplication No. 2006-12303, which has been filed in the name of theapplicant of the present application. In the disclosure of this patentapplication, the unit module is configured to have a structure in whichtwo secondary batteries are mounted to a frame member having input andoutput terminals in a state in which the secondary batteries are intight contact with each other.

Another example of the unit module is disclosed in Korean PatentApplication No. 2006-20772 and No. 2006-45444, which have also beenfiled in the name of the applicant of the present application. In thedisclosure of each of these patent applications, the unit module isconfigured to have a structure in which outer sides of two secondarybatteries are covered with a pair of high-strength cell covers in astate in which the secondary batteries are in tight contact with eachother.

The disclosures of the above patent applications are incorporated hereinby reference. Of course, however, the structure of each of the unitmodules of the battery module according to the present invention is notlimited to the above examples of the unit modules disclosed in the abovepatent applications.

Preferably, each of the battery cells is a plate-shaped battery cell,which provides a high stack rate in a limited space. For example, eachof the battery cells may be configured to have a structure in which anelectrode assembly is mounted in a battery case formed of a laminatesheet.

Specifically, each of the battery cells is a pouch-shaped secondarybattery in which an electrode assembly of a cathode/separator/anodestructure is disposed in a battery case together with an electrolyte ina sealed state. For example, each of the battery cells may be aplate-shaped secondary battery configured in an approximately hexahedralstructure having a small thickness to width ratio. Generally, thepouch-shaped secondary battery includes a pouch-shaped battery case. Thebattery case is configured to have a laminate sheet structure in whichan outer coating layer formed of a polymer resin exhibiting highdurability, a barrier layer formed of a metal material blocking moistureor air, and an inner sealant layer formed of a polymer resin that can bethermally welded are sequentially stacked.

The structure of each of the main members is not particularly restrictedso long as each of the main members can easily support load of thebattery modules. Preferably, each of the main members is configured tohave an approximately U-shaped frame structure surrounding oppositesides and the bottom of the battery module array.

Consequently, the opposite sides of each of the main members areconnected to a corresponding one of the end plates with the result thatthe interior of the U-shaped frame structure is full, and therefore,bending rigidity of each of the main members against vertical vibrationis greatly improved.

In a preferred example of the above-described structure, upper ends ofeach of the main members may be bent outward so that the battery packcan be easily mounted to an external device, and the bent portions ofeach of the main members may be provided with fastening holes.Consequently, coupling between the main members and the external deviceis securely achieved.

The structure of the reinforcement member is not particularly restrictedso long as the reinforcement member can prevent deformation of thebattery pack when external force is applied to the battery pack in thefront and rear direction. For example, the reinforcement member may beformed in the shape of a plate or bar and may be disposed at the outerside of the outermost battery module in a diagonal structure or in anX-shaped structure on a plane.

Specifically, the side shape of each of the main members may be deformedfrom a rectangular shape to a parallelogram when the battery pack isdeformed in the front and rear direction. In the diagonal structure,therefore, each of the main members is constrained in the diagonaldirection in a state in which the side shape of each of the main membersis maintained in the rectangular shape, thereby increasing resistanceagainst deformation of the battery pack in the front and rear direction.

Also, in the X-shaped structure, it is possible to greatly improveresistance against deformation of the battery pack in the front and reardirection as compared with the diagonal structure.

The reinforcement member may be coupled to the side walls of the endplates or the sides of the main members by welding or bolting as needed.

According to circumstances, the reinforcement member may be furthercoupled to tops of the end plates by welding or bolting so that thereinforcement member is disposed in a diagonal structure or in anX-shaped structure on a plane, thereby more effectively preventingdeformation of the battery pack when the battery pack is vibrated in theup and down direction and in the front and rear direction.

Meanwhile, each of the end plates may be formed in the shape of a singlebody having a size corresponding to the front or rear of the batterymodule array to minimize deformation of the battery pack when thebattery pack is vibrated in the up and down direction.

In such a structure in which each of the end plates has a sizecorresponding to the front or rear of the battery module array asdescribed above, it is possible to reliably improve bending rigidity ofthe main members and to sufficiently secure overall structural stabilityof the battery pack when the battery pack is vibrated in the up and downdirection.

Each of the end plates may be configured to disperse pressure (bendingload) from the battery modules and the supporting bars. Preferably, eachof the end plates includes a body part disposed in contact with thebattery module array, an upper end wall, a lower end wall, and a pair ofside walls, the upper end wall, the lower end wall, and the side wallsprotruding outward from the perimeter of the body part. Here, “outwarddirection” means a direction opposite to the pressure, i.e. a directionopposite a direction in which the battery modules and the supportingbars are located about the body part of each of the end plates.

In the battery pack according to the present invention, therefore, thebattery modules, which are stacked on the base plate, are brought intotight contact with each other by the end plates, and the end plates arefixed by the supporting bars. Consequently, it is possible to preventthe unit modules constituting each of the battery modules from moving inthe thickness direction thereof and swelling, thereby improving safetyof the battery modules and effectively preventing deterioration inperformance of the battery modules.

In a preferred example of the above-described structure, the lower endwall of each of the end plates may be coupled to the lower end of thebase plate and the lower end of each of the main members by welding orbolting.

In a case in which the lower end wall of each of the end plates iscoupled to the lower end of the base plate and the lower end of each ofthe main members by welding or bolting, the welding or the bolting ispreferably carried out at four or more spots, thereby achieving securecoupling therebetween.

In another example, each of the side walls of each of the end plates mayalso be coupled to each side of each of the main members by welding orbolting.

In a case in which each of the side walls of each of the end plates iscoupled to each side of each of the main members by welding or bolting,the welding or bolting may be carried out at one or more spots. Inparticular, coupling between the end plates and the main members isimproved when the welding or the bolting is carried out at three or morespots in consideration of modes in which the main members are deformed.

Meanwhile, the supporting bars may interconnect the upper parts and/orthe side parts of the end plates.

In a structure in which the supporting bars interconnect the upper partsof the end plates, the upper end wall of each of the end plates mayprotrude upward from the top of the battery module array so that thesupporting bars can be easily mounted to the end plates. In thisstructure, the supporting bars may be coupled to the end plates in astate in which the supporting bars are located above the batterymodules.

The upwardly protruding height of the upper end wall may be equivalentto 2 to 20% of the height of the battery module array. If the upwardlyprotruding height of the upper end wall is less than 2% of the height ofthe battery module array, it is difficult to mount the supporting barsto the end plates. Alternatively, supporting bars having a correspondingsize may be used. In this case, however, overall rigidity of the batterypack is lowered. On the other hand, if the upwardly protruding height ofthe upper end wall is greater than 20% of the height of the batterymodule array, the volume of the battery pack is excessively increased,which is not preferable.

Since the lower end walls of the end plates are fixedly coupled to thebase plate, the end plates are prevented from being separated from thebase plate when external impact is applied to the end plates.

For example, a pair of fastening holes may be formed at a portion of thelower end wall of each of the end plates, and bolts may be insertedthrough the fastening holes so that the end plates can be fixed to thebase plate. Alternatively, coupling between the end plates and the baseplate may be achieved by welding.

Meanwhile, the size of each of the end plates is not particularlyrestricted so long as each of the end plates has a size corresponding tothe front or rear of the battery module array. For example, each of theend plates may be formed in the planar shape of a rectangle.

Preferably, each of the end plates is provided at the upper part thereofwith through holes, in which the supporting bars are mounted. Thesupporting bars are inserted through the through holes, thereby easilyachieving coupling between the end plates and the supporting bars.

In accordance with another aspect of the present invention, there isprovided a device such as an electric vehicle, hybrid electric vehicle,or plug-in hybrid electric vehicle using the battery pack with theabove-stated construction as a power source, having a limitedinstallation space, and exposed to frequent vibration and strong impact.

Of course, the battery pack used as the power source of the vehicle maybe combined and manufactured based on desired power and capacity.

In this case, the vehicle may be an electric vehicle, hybrid electricvehicle, or plug-in hybrid electric vehicle wherein the battery pack isinstalled in the lower end of a trunk of the vehicle or between a rearseat and the trunk of the vehicle.

The electric vehicle, hybrid electric vehicle, or plug-in hybridelectric vehicle using the battery pack as the power source thereof arewell known in the art to which the present invention pertains, andtherefore, a detailed description thereof will not be given.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a perspective view showing a conventional battery pack;

FIG. 2 is a perspective view showing a battery pack according to anembodiment of the present invention;

FIG. 3 is a perspective view showing a battery pack according to anotherembodiment of the present invention;

FIG. 4 is a perspective view showing the structure of a comparativebattery pack in which no reinforcement member is mounted, which iscompared with the structure of the battery pack according to the presentinvention shown in FIG. 2;

FIGS. 5 and 6 are perspective views showing variation when externalforce is applied to the battery packs shown in FIGS. 2 and 4 in thefront and rear direction;

FIGS. 7 and 8 are perspective views showing variation when externalforce is applied to the battery packs shown in FIGS. 2 and 4 in the upand down direction; and

FIGS. 9 and 10 are perspective views showing battery packs according toother embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Now, exemplary embodiments of the present invention will be described indetail with reference to the accompanying drawings. It should be noted,however, that the scope of the present invention is not limited by theillustrated embodiments.

FIG. 2 is a perspective view typically showing a battery pack accordingto an embodiment of the present invention.

Referring to FIG. 2, a battery pack 200 includes a battery module array122 including battery modules 110 and 120 which are arranged in thelateral direction in two rows, a base plate 130, a pair of main members140, a pair of end plates 150, and a plurality of supporting bars 160.

The battery modules 110 and 120 are stacked on the top of the base plate130 in a state in which the battery modules 110 and 120 are verticallyerected. The end plates 150 are disposed in tight contact with the frontand rear of the a battery module array 122 in a state in which the lowerends of the end plates 150 are fixed to the base plate 130.

The main members 140 are provided at the front and rear of the batterymodule array 122 to support load of the battery modules 110 and 120.Opposite ends of each of the main members 140 are fastened to anexternal device (not shown).

Also, each of the main members 140 is configured to have a U-shapedframe structure surrounding opposite sides and the bottom of the batterymodule array 122. The upper ends of each of the main members 140 arebent outward. The bent portions of each of the main members 140 areprovided with fastening holes 142, through which the battery pack 200can be easily mounted to an external device.

The supporting bars 160 are connected between the upper parts of the endplates 150 so as to interconnect and support the end plates 150.

Also, a reinforcement member 170 is coupled to the side walls of the endplates 150 by welding so that the reinforcement member 170 is disposedat the outer side of the outermost battery module 110 in a diagonalstructure on a plane to minimize deformation of the battery pack 200when the battery pack 200 is vibrated in the front and rear direction.

According to circumstances, the reinforcement member 170 may be coupledto the side walls of the end plates 150 by bolting (not shown).

On the other hand, each of the end plates 150 is formed in the planarshape of a rectangle having a size corresponding to the front of thebattery module array 122 to minimize deformation of the battery pack 200when the battery pack 200 is vibrated in the up and down direction.

Also, each of the end plates 150 includes a body part 152 disposed incontact with the battery module array 122, an upper end wall 154, alower end wall 156, and a pair of side walls 158. The upper end wall154, the lower end wall 156, and the side walls 158 protrude outwardfrom the perimeter of the body part 152.

The lower end wall 156 of each of the end plates 150 is coupled to thelower end of the base plate 130 and the lower end of each of the mainmembers 140 at four spots 151 by spot welding. Each of the side walls158 of each of the end plates 150 is coupled to each side of each of themain members 140 at three spots 153 by spot welding.

According to circumstances, the lower end wall 156 of each of the endplates 150 may be coupled to the lower end of the base plate 130 and thelower end of each of the main members 140 by bolting (not shown). In thesame manner, each of the side walls 158 of each of the end plates 150may be coupled to each side of each of the main members 140 by bolting(not shown).

In addition, the upper end wall 154 of each of the end plates 150protrudes upward from the top of the battery module array 122 so thatthe upper end wall 154 of each of the end plates 150 is 10% higher thanthe height H of the battery module array 122. Consequently, thesupporting bars 160 can be easily mounted to the upper parts 155 of theend plates 150.

The battery module 110 is configured to have a structure in which unitmodules each including plate-shaped battery cells, each of which has anelectrode assembly mounted in a battery case formed of a laminate sheet,are stacked in a state in which the unit modules are vertically erected.

FIG. 3 is a perspective view typically showing a battery pack accordingto another embodiment of the present invention.

Referring to FIG. 3, a battery pack 200 a of FIG. 3 is identical instructure to the battery pack 200 of FIG. 2 except that each of the endplates 150 is provided at the upper part thereof with through holes 157,in which the supporting bars 160 are mounted, and a reinforcement member172 is coupled to the side walls of the end plates 150 by welding sothat the reinforcement member 172 is disposed at the outer side of theoutermost battery module 110 in an X-shaped structure on a plane, andtherefore, a detailed description thereof will not be given.

FIG. 4 is a perspective view typically showing the structure of acomparative battery pack in which no reinforcement member is mounted,which is compared with the structure of the battery pack according tothe present invention shown in FIG. 2.

Referring to FIG. 4 together with FIG. 2, a battery pack 200 b of FIG. 4is identical in structure to the battery pack of FIG. 2 except that thereinforcement member 170 is not coupled to the side walls of the endplates 150 by welding so that the reinforcement member 170 is disposedat the outer side of the outermost battery module 110 in a diagonalstructure on a plane.

FIGS. 5 and 6 are perspective views typically showing variation whenexternal force is applied to the battery packs shown in FIGS. 2 and 4 inthe front and rear direction. Structures shown in FIGS. 5 and 6 andstructures shown in FIGS. 7 and 8, which will be described below, areobtained by simulating variation when external force is applied to thebattery packs.

Referring to these drawings, when external force is applied to thebattery pack 200 of FIG. 2 in the front and rear direction (in adirection indicated by an arrow), deformation of the main members 140and the battery module 110 is low since the reinforcement member 170supports the main members 140. On the other hand, when external force isapplied to the battery pack 200 b of FIG. 4, deformation of the mainmembers 140 and the battery module 110 b is high in the front and reardirection, i.e. the direction in which the external force is applied tothe battery pack 200 b.

FIGS. 7 and 8 are perspective views typically showing variation whenexternal force is applied to the battery packs shown in FIGS. 2 and 4 inthe up and down direction.

Referring to these drawings, when external force is applied to thebattery pack 200 of FIG. 2 in the up and down direction (in a directionindicated by an arrow), deformation of the main members 140 is low sincethe reinforcement member 170 supports the main members 140. On the otherhand, when external force is applied to the battery pack 200 b of FIG.4, deformation of the main members 140 b is high in the direction inwhich the external force is applied to the battery pack 200 b.

Meanwhile, resonance point detection and analysis have been carried outin deformation modes when external force was applied to the batterypacks in the front and rear direction and in the up and down directionso as to understand vibration properties of the battery pack structureshown in FIG. 2 and the battery pack structure shown in FIG. 4. Theresults of the resonance point detection and analysis are given in Table1 below.

TABLE 1 Deformation mode Structure of battery pack Resonance frequencyDeformation mode in Structure of FIG. 2 71.467 Hz front and reardirection Structure of FIG. 4 16.588 Hz Deformation mode in Structure ofFIG. 2 73.779 Hz up and down direction Structure of FIG. 4 73.572 Hz

As can be seen from Table 1 above, in each of the deformation modes,structural stability of the battery pack of FIG. 2 is improved ascompared with that of the battery pack of FIG. 4 even when the batterypack is strongly vibrated in the up and down direction or in the frontand rear direction since the battery pack of FIG. 2 is configured tohave a structure in which the reinforcement member is coupled to theside walls of the end plates by welding. In particular, the structuralstability of the battery pack is higher when the battery pack isvibrated in the front and rear direction.

Consequently, it is possible to minimize variation of the main membersin the front and rear direction by simply fixing the reinforcementmember to the side walls of the end plates, which is an unexpectedresult.

Particularly, in the battery pack according to the present invention,the reinforcement members are coupled to the side walls of the endplates by welding at the outer side of the outermost battery module ofthe battery module array. Consequently, the present invention can beapplied to a vehicle in which the weight of the battery pack is 30 Kg ormore, and the main members of the battery pack poorly tolerate vibrationin the front and rear direction.

FIGS. 9 and 10 are perspective views showing battery packs according toother embodiments of the present invention.

Referring to these drawings, a battery pack 200 c of FIG. 9 is identicalin structure to the battery pack 200 of FIG. 2 except that areinforcement member 174 is coupled to sides of main members 140 c bywelding so that the reinforcement member 174 is disposed at the outerside of the outermost battery module 110 in a diagonal structure on aplane, and a battery pack 200 d of FIG. 10 is identical in structure tothe battery pack 200 of FIG. 2 except that a reinforcement member 175 isfurther coupled to tops of the end plates 150 by welding so that thereinforcement member 174 is disposed in a diagonal structure on a plane,and therefore, a detailed description thereof will not be given.

INDUSTRIAL APPLICABILITY

As is apparent from the above description, the battery pack according tothe present invention is configured to have a structure in which thebattery modules are arranged in the lateral direction in two or morerows. Consequently, it is possible for the battery pack according to thepresent invention to provide higher power and capacity than aconventional battery pack including a single battery module.

Also, the battery pack according to the present invention is configuredto have a structure in which the reinforcement member is coupled to theside walls of the end plates or the sides of the main members at theouter side of the outermost battery module of the battery module array.Consequently, it is possible to minimize deformation of the battery packwhen the battery pack is vibrated in the front and rear direction.

In addition, a portion of the battery pack is configured using a portionof a vehicle. Consequently, it is possible to stably install the batterypack in the vehicle and to minimize the volume occupied by the batterypack in the vehicle.

Although the exemplary embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

The invention claimed is:
 1. A battery pack comprising: a battery modulearray having battery modules which are arranged in a lateral directionin two or more rows, each of the battery modules being configured tohave a structure in which battery cells or unit modules, each of whichhas two or more battery cells mounted therein, stacked in a state inwhich the battery cells or the unit modules are vertically erected; abase plate on which the battery modules are stacked in a verticallyerected state; a pair of main members provided at a front and rear ofthe battery module array to support load of the battery modules,opposite ends of each of the main members being fastened to an externaldevice; a pair of end plates disposed in tight contact with the frontand rear of the battery module array in a state in which a lower end ofeach of the end plates is fixed to the base plate; and supporting barsconnected between upper parts or side parts of the end plates so as tointerconnect and support the end plates, wherein a reinforcement memberis coupled to side walls of the end plates or sides of the main membersat an outer side of an outermost battery module of the battery modulearray to minimize deformation of the battery pack when the battery packis vibrated in a front and rear direction, and wherein each of the mainmembers is configured to have a U-shaped frame structure surroundingopposite sides and a bottom of the battery module array.
 2. The batterypack according to claim 1, wherein each of the battery cells is aplate-shaped battery cell.
 3. The battery pack according to claim 2,wherein each of the battery cells is configured to have a structure inwhich an electrode assembly is mounted in a battery case formed of alaminate sheet.
 4. The battery pack according to claim 1, wherein upperends of each of the main members are bent outward so that the batterypack can be easily mounted to an external device, and the bent portionsof each of the main members are provided with fastening holes.
 5. Thebattery pack according to claim 1, wherein the reinforcement member isdisposed at the outer side of the outermost battery module in a diagonalstructure or in an X-shaped structure on a plane.
 6. The battery packaccording to claim 1, wherein the reinforcement member is coupled to theside walls of the end plates or the sides of the main members by weldingor bolting.
 7. The battery pack according to claim 1, wherein thereinforcement member is further coupled to tops of the end plates bywelding or bolting so that the reinforcement member is disposed in adiagonal structure or in an X-shaped structure on a plane.
 8. Thebattery pack according to claim 1, wherein each of the end plates isformed in the shape of a single body having a size corresponding to thefront or rear of the battery module array to minimize deformation of thebattery pack when the battery pack is vibrated in an up and downdirection.
 9. The battery pack according to claim 1, wherein each of theend plates comprises a body part disposed in contact with the batterymodule array, an upper end wall, a lower end wall, and a pair of sidewalls, the upper end wall, the lower end wall, and the side wallsprotruding outward from a perimeter of the body part.
 10. The batterypack according to claim 9, wherein the lower end wall of each of the endplates is coupled to a lower end of the base plate and a lower end ofeach of the main members by welding or bolting.
 11. The battery packaccording to claim 10, wherein the welding or the bolting is carried outat four or more spots.
 12. The battery pack according to claim 9,wherein each of the side walls of each of the end plates is coupled toeach side of each of the main members by welding or bolting.
 13. Thebattery pack according to claim 12, wherein the welding or the boltingis carried out at one or more spots.
 14. The battery pack according toclaim 9, wherein the upper end wall of each of the end plates protrudesupward from a top of the battery module array so that the supportingbars can be easily mounted to the end plates.
 15. The battery packaccording to claim 14, wherein the upwardly protruding height isequivalent to 2 to 20% of a height of the battery module array.
 16. Thebattery pack according to claim 1, wherein each of the end plates isformed in the planar shape of a rectangle.
 17. The battery packaccording to claim 1, wherein each of the end plates is provided at anupper part thereof with through holes, in which the supporting bars aremounted.
 18. An electric vehicle using the battery pack according toclaim 1 as a power source.
 19. The device according to claim 18, whereinthe battery pack is installed in a lower end of a trunk of the vehicleor between a rear seat and the trunk of the vehicle.
 20. A hybridelectric vehicle using the battery pack according to claim 1 as a powersource.
 21. A plug-in hybrid electric vehicle using the battery packaccording to claim 1 as a power source.